Seventy-five former NFL football players are suing the NFL for neglecting to properly inform them of concussion dangers. The lawsuit was sparked in part, due to the death of NFL star Dave Duerson, who was found to have chronic traumatic encephalopathy which is caused by repeated brain trauma. Duerson was known as a fierce defensive hitter and sustained many hard hits to his head. He had requested his brain be donated for scientific study because he knew his mental health had declined during retirement to the point he had difficulty speaking normally, at times. The disease has been found in more than twenty deceased NFL football players.